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Chemistry 242
Final Exam
Summer 2009
The final exam for this course will be given
. It will be on the material in Chapters 8, 10 – 21,
and 24 - 26 that we have covered in class
The following textbook sections will be covered on the exam:
Chapter 8: sections 8.1, 8.2, 8.8, 8.9 only
Chapter 10: sections 10.1, 10.4 - 10.8 only
Chapter 11: all except 11.1, 11.12, 11.13
Chapter 13: sections 13.8 – 13.11, 13.13
Chapter 14: sections 14.1 and 14.3 only
Chapter 15: sections 15.2 - 15.6 15.10
Chapter 16: all except 16.8, 16.9
Chapter 17: all except 17.9, 17.10, 17.11
Chapter 18: section 18.1, 18.3
Chapter 19: all except .9 .12 –.15
Chapter 20: all except 20.5
Chapter 21: all except 21.8, 21.9
Chapter 24: 24.1, 24.2, 24.4 24.6
Chapter 26: 26.1, 26.5, 26.6
Chapter 28 ??
It is particularly important to study and do the problems for the following sections:
8.9
10.7 10.8
11.4 11.5 11.9 11.11
13.8
13.11
14.1
15.5
16.1
16.5 16.6
17.4 to 17.7
19.4 19.8 19.11
20.6
21.2 21.3 21.6
24.6
25.5 25.10
Some sections NOT on the final exam: 11.1 13.1-13.7 17.9 19.9 12.12 21.9 24.6
Topics that may be covered on the final:
What are the products of free radical halogenation of an alkane (ex: Cl2/hv light)? What is the
electivity for brominations vs. chlorinations?
How are alkyne anions formed from terminal alkynes?
Which radical or anion is most stable?
Proper names for compounds containing functional groups covered this semester.
What are the nucleophiles and electrophiles in these reactions?
Give the product for the following E2 elimination reaction.
What is the Williamson ether synthesis? How is it used?
Given a molecular formula and NMR spectrum, determine the structure for a compound.
1
H NMR spectroscopy: chemical shift, integration, and the n+1 rule for splitting. (no 13C NMR)
What is the degree of unsaturation for a given molecular formula.
Draw out the splitting pattern for the following structure.
Which systems are conjugated? Which are aromatic? (4n+2 rule)
For aromatic substitution reactions, does a specific substituent direct ortho, meta, or para?
Which substituent is a more powerful directing group?
How would you synthesize the following di- or trisubstituted benzene?
Which compound is more acidic? Which is more basic?
Which of the carboxylic acid derivatives is the most stable? Which is the most reactive? Why?
Preparation and carboxylic acid derivatives and conversion to other derivatives.
Synthesis problems – know reactions needed to make an organic molecule from an alkane.
Know the following electrophilic aromatic substitution reactions:
Bromination (Br2/FeBr3)
Chlorination (Cl2/FeCl3)
HNO3/cat. H2SO4 (nitration)
Sulfonation - fuming sulfuric acid (SO3/H2SO4)
RC(=O)Cl / AlCl3 (Friedel-Crafts Acylation) R-X / AlCl3 (Friedel-Crafts Alkylation)
Other aromatic topics:
Ph-NO2
Ph-NH2 (reduction/oxidation) Ph-CO-R
Ph-CH2-R (reduction/oxidation)
Sulfonate as a temporary blocking group
Synthesis of disub. aromatic compounds
NMR
Chemical shift regions, coupling patterns, integration, equivalent protons (skip 13C NMR)
Be able to determine a structure from an NMR spectrum and the molecular formula!
Reagents for Haloalkanes (X = F, Cl, Br, I):
SOCl2 and PBr3 (R-OH to R-X for 1° alcohols)
HCl / HBr (R-OH to R-X for 3° alcohols)
NBS (allylic bromination)
Alkene plus X2 or HX - addition to double bond (Markovnikov selectivity)
Preparation of Alcohols:
Hydration of alkenes: acid-catalyzed addition of water (Markov.) or BH3/ox (Anti-Markov.)
Reduction of carbonyl compounds: NaBH4 (ald/ketones), LiAlH4 (ald/ketones/acids/esters)
SN2 reaction of an unhindered alkyl halide R-X with OH- to form the alcohol R-OH
**Addition of Grignards or R-Li to aldehydes and ketones: mechanism, limitations
Reactions of Alcohols:
Deprotonation with strong base (NH2-, K metal) to form the alkoxide anion RO–
Oxidation to carbonyl - PCC or CrO3 (know when to use which reagent)
Conversion to R-X - HBr (dry, for 3° alcohols), PBr3, SOCl2 (for 1° and 2° alcohols)
Elimination to alkenes - POCl3 (1° and 2°) or H2SO4 (for 3° alcohols)
Aldehydes and Ketones
Preparation – from oxidation of primary or secondary alcohols
Addition of nucleophiles to the carbonyl carbon (Nu = H-, RLi, RMgX, CN-)
Acetal formation and use as a protecting group.
Carboxylic Acids and Derivatives:
Reactivity of derivatives: acid chlorides most reactive, amides least reactive
Hydrolysis of acid chlorides, anhydrides, esters, amides, and nitriles to carboxylic acids
Preparation and reaction of carboxylic acids and their derivatives
Amines
Synthesis of amines: amide + LiAlH4
nitrile hydrolysis
ammonia + R-X (SN2)
Amino Acids and Proteins
Amino acids, peptide bonds, and protein structures (1°, 2°, and 3° structure).
Identify valid α-amino acids and peptides that could be found in nature.
Know the following reaction mechanisms:
SN1/SN2/E1/E2 reactions: SN2/E2 transition states and SN1/E1 intermediates
Electrophilic aromatic substitution – draw out resonance structures for the cationic intermediate
Acetal formation (acid catalyzed)
Fisher esterification (acid catalyzed)
Nucleophilic acyl substitution (up-down-out) Example: acid chloride + alcohol to give ester
Synthesis of a target compound, starting from a hydrocarbon or other simple molecule.
Drawing proper structures for isomers of a given molecular formula.
What do PCC, CrO3, SOCl2, PBr3, NaBH4, LiAlH4, POCl3, Mg, CO2, NBS, HCl, R-Li, t-butoxide do?
Skip: 13C NMR, alcohol protection w/ Me3SiCl, Wolff-Kishner, Imine formation
Reaction Summaries
Substitution/Elimination
Nucleophile - strength of a nucleophile increases when:
adding a negative charge
RO- stronger than ROH
moving left on the periodic table
NH2- stronger than OHmoving down the periodic table
PH3 stronger than NH3
Bases - base strength increased by:
addition of a negative charge
RO- stronger than ROH
moving left on the periodic table
NH2- stronger than OHmoving up the periodic table
NH3 stronger than PH3
Leaving Group - good leaving groups are –OTos, –I, –Br, –Cl, and any neutral fragment (H2O)
poor leaving groups are –OH, –NH2, –OR, –CH3
Key Factors for Reaction Mechanisms
SN2 Reactions – unhindered electrophile (1°, maybe 2° R-X, but NOT 3°), good nucleophile
SN1 Reactions – stable carbocation (3°, allylic, benzylic), protic solvent (ROH or H2O), no strong base
E2 Reactions – strong base and an H next door to the leaving group; t-butoxide will promote E2
E1 Reactions - stable carbocation (3° or allylic, benzylic), protic solvent (ROH or H2O), weak base
Electrophilic Aromatic Substitution (EAS)
Directing power of various benzene substituents:
Group I (-OR, -NH2)
Group II (-X, -alkyl)
Group III (all meta directors)
Summary of Benzene Substituents
Activators:
add electron density to aromatic ring, speed up the rate of EAS, direct ortho/para
can add e- density by induction (-alkyl groups)
can add e- density by resonance (-OH, -OR, -NR2, -Ph )
Deactivators: remove electron density from aromatic ring, reduce rate of EAS, direct meta
can remove e- density by induction (-CF3, -N+R3, -SO3H, -NO2 )
can remove e- density by resonance (-NO2, -CN, -C(=O)-R carbonyl)
Halogens: deactivators that are ortho/para directors